Magnetic and optical disk drives store and retrieve data for digital electronic apparatuses such as computers. A typical disk drive comprises a head, including a slider and a transducer, in very close proximity to a surface of a rotatable disk. The transducer, in turn, includes a write element and/or a read element. As the disk rotates beneath the head, a very thin air bearing is formed between the surface of the disk and an air bearing surface of the slider. The air bearing causes the head to “fly” above the surface of the disk. As the head flies over the disk, the write element and the read element can be alternately employed to write and read data bits along a data track on the disk.
In order to keep the head properly oriented and at the correct height above the disk while in flight, and to move the head from one track to another, disk drives employ a head gimbal assembly (HGA) and voice coil actuator assembly. The HGA typically comprises the head and a suspension assembly that further includes a load beam, a gimbal that attaches the head to the load beam, and a swage mount.
The voice coil actuator assembly comprises a fixed magnet assembly and a pivoting actuator arm. One side of the actuator arm secures the load beam while the other side includes a voice coil. The voice coil is configured to move laterally within the magnet assembly. Translating the head is achieved by varying an electric current applied to the voice coil. Varying the current causes the voice coil to move laterally within the magnet assembly which rotates the actuator arm around the pivot, thus translating the head.
Most high capacity disk drives employ a stack of several closely spaced disks, and for each disk there are two heads, one positioned above the disk and one positioned below. If the head is disposed “above” one of the disks (i.e. closer to the disk drive top cover than the disk) of the disk stack and faces “downward” (i.e. away from the top cover), then the head is termed a “down head,” otherwise the head is termed an “up head.” It will be understood that the designations of “up” and “down” and “upward” and “downward” in this context, can be chosen arbitrarily by the disk drive designer to create a convenient terminology convention, and should not be understood to necessarily accord with any external frame of reference such as gravity.
FIG. 1 illustrates an exemplary head stack assembly (HSA) 100 for use in conjunction with a disk stack (not shown) in a high capacity disk drive. The HSA 100 comprises a pivot bearing cartridge, an actuator body, a coil, a coil support, and a number of HGAs 110 attached to a plurality of actuator arms 120 of the actuator body. The HSA 100 also comprises a flex clip and a preamp. Each HGA 110 comprises a suspension assembly, including a load beam 130, and a head 140.
As shown in FIG. 2, electrical components such as the transducer on each head 140 are able to communicate with circuits of the disk drive, or with testing circuits of a component tester for testing purposes prior to assembly, through a set of electrical traces 200 on a support that is sometimes referred to as a flexure tail 210. The flexure tail 210 extends along the length of the load beam 130 and the actuator arm 120 (FIG. 1). A set of bonding pads 220 are disposed at an end 230 of the flexure tail 210 to allow the head 140 to be connected to the circuitry of the disk drive. When multiple HGAs 110 are assembled to form the HSA 100 (FIG. 1), the bonding pads 220 of each flexure tail 210 are soldered to connectors at an end of a flex cable 150 (FIG. 1) to complete the disk drive circuits. An out of plane bend 240 in the flexure tail 210 allows the bonding pads 220 to lie in a plane that is perpendicular to a plane defined by the load beam 130 for assembly to the end of the flex cable 150.
It will be appreciated that the ends 230 of the flexure tails 210 from each of the heads 140 of the HSA 100 are bonded to the same flex cable 150, and a height of the flex cable 150 is limited by at least a height of the interior of the drive enclosure. Effectively, therefore, a height, h, of the end 230 of the flexure tail 210 is essentially limited to about half of the disk-to-disk spacing of the disk stack so that two ends 230 can fit the space between two adjacent disks of the disk stack. Due to the narrowness of the disk-to-disk spacing in current disk drives, the height, h, of the end 230 must be small. Accordingly, the bonding pads 220 on the end 230 of the flexure tail 210 are arranged in a single row.
Increasingly sophisticated disk drives are being designed that require HGAs having additional electrical components beyond just the read and write transducers (e.g. microactuators, heaters for dynamic fly height control, etc.), and each additional electrical component requires further bonding pads on the end of the flexure tail. However, other dimensional limitations of the connector at the end of the flex cable 150 prevent the ends 230 from becoming increasingly long, and soldering and other electrical connection requirements prevent bonding pads 220 from being made smaller and more closely spaced. Accordingly, accommodating additional electrical components poses a problem for joining flexure tails 210 to flex cables 150.